DESCRIPTION: (lifted from Abstract): Histatins (Hst) are one of the major salivary proteins that appear to have fungicidal activity in the mouth. Oropharyngeal candidiasis (OPC) in HIV-infected individuals may be the result of an alteration in the interactions between Hst and Candida albicans. These researchers have identified a surface protein on Candida, HstBP, that may be the receptor or binding protein for Hst. They suggest that HstBP may be related to efflux pumps such as the ABC transporters or the Major Facilitator superfamily. They hypothesize that OPC may be the result of Candida strains with altered expression of HstBP. They propose to characterize HstBP expression as an underlying mechanism in the development of candidiasis in HIV patients by the following specific aims: 1. Purify HstBP by standard biochemical methods, clone and sequence the HstBP gene. 2. Define the biologic role of HstBP by identifying common structural features, and by assessing the effects of certain physiological mediators on HstBP. 3. Compare HstBP expression in yeasts that are sensitive or resistant to Hst from patients with OPC by determining HstBP molecules/cell using standard binding assays and by levels of mRNA expression using Northern blot analysis.